import java.util.Scanner;

public class NumFactorial {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        int x=sc.nextInt();
        int n=numFactorial(x);
        System.out.println(x+"的阶乘为"+n);
    }
    public static int numFactorial(int num){
        if(num==1){
            return 1;
        }
        int n=numFactorial(num-1);
        return num*n;
    }
}
